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Prenormative verification and validation of a protocol for measuring magnetite-maghemite ratios in magnetic nanoparticles

Bogart, LK; Fock, J; da Costa, GM; Witte, K; Greneche, J-M; Zukrowski, J; Sikora, M; ... Pankhurst, QA; + view all (2022) Prenormative verification and validation of a protocol for measuring magnetite-maghemite ratios in magnetic nanoparticles. Metrologia , 59 (1) , Article 015001. 10.1088/1681-7575/ac36b6. Green open access

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Abstract

An important step in establishing any new metrological method is a prenormative interlaboratory study, designed to verify and validate the method against its stated aims. Here, the 57Fe Mössbauer spectrometric 'centre of gravity' (COG) method was tested as a means of quantifying the magnetite/maghemite (Fe3O4/γ-Fe2O3) composition ratio in biphasic magnetic nanoparticles. The study involved seven laboratories across Europe and North and South America, and six samples—a verification set of three microcrystalline mixtures of known composition, and a validation set of three nanoparticle samples of unknown composition. The spectra were analysed by each participant using in-house fitting packages, and ex post facto by a single operator using an independent package. Repeatability analysis was performed using Mandel's h statistic and modified Youden plots. It is shown that almost all (83/84) of the Mandel h statistic values fall within the 0.5% significance level, with the one exception being borderline. Youden-based pairwise analysis indicates the dominance of random uncertainties; and in almost all cases the data analysis phase is only a minor contributor to the overall measurement uncertainty. It is concluded that the COG method is a robust and promising candidate for its intended purpose.

Type: Article
Title: Prenormative verification and validation of a protocol for measuring magnetite-maghemite ratios in magnetic nanoparticles
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/1681-7575/ac36b6
Publisher version: https://doi.org/10.1088/1681-7575/ac36b6
Language: English
Additional information: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10140926
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